Isotopic tracer composition and method for making and using same

Abstract

An isotopic tracer composition and methods of making and using same for radiological evaluation of body functions and diseases in a subject and for radiological therapy. The isotopic tracer composition comprises a protein carrier agent such as fibrinogen, antibodies, enzymes or portions thereof, bound to a radioisotope which has been reduced to a lower oxidation state by stannous phosphate at a pH of greater than 7. Some suitable radioisotopes are isotopes of technetium, rhenium and ruthenium.

What is claimed is: 
     
       1. A method for preparing an isotopic tracer composition comprising a protein or fragment thereof and a radioisotope characterized by the ability to bind a protein or fragment thereof when treated with a sufficient amount of stannous phosphate, consisting of the steps of: contacting an effective amount of the radioisotope with an amount of stannous phosphate which is sufficient to reduce a substantial amount of the radioisotope to a lower oxidation state at a pH greater than 7; and   exposing an effective amount of the protein or fragment thereof to the reduced radioisotope at a pH greater than 7 thereby binding the protein or fragment thereof to the radioisotope.   
     
     
       2. The method of claim 1 wherein the protein is fibrinogen. 
     
     
       3. The method of claim 1 wherein the protein is an antibody. 
     
     
       4. The method of claim 1 wherein the protein is an enzyme. 
     
     
       5. The method of claim 1 wherein the radioisotope is an isotope of Rhenium. 
     
     
       6. The method of claim 5 wherein the isotope of Rhenium is Re-186. 
     
     
       7. The method of claim 5 wherein the isotope of Rhenium is Re-188. 
     
     
       8. The method of claim 1 wherein the radioisotope is an isotope of Ruthenium. 
     
     
       9. The method of claim 8 wherein the isotope of Ruthenium is Ru-97. 
     
     
       10. The method of claim 1 wherein the radioisotope is an isotope of Technetium. 
     
     
       11. The method of claim 10 wherein the isotope of Technetium is Tc-99m. 
     
     
       12. A method for preparing an isotopic tracer composition comprising a protein or fragment thereof and a radioisotope characterized by the ability to bind a protein or fragment thereof when treated with a sufficient amount of stannous phosphate, consisting of the steps of: contacting an effective amount of the radioisotope with an amount of stannous phosphate at a pH greater than 7 which is sufficient to reduce a substantial amount of the radioisotope to a lower oxidation state;   exposing an effective amount of the protein or fragment thereof to the reduced radioisotope at a pH greater than 7 thereby binding the protein or fragment thereof to the radioisotope forming an isotopic tracer composition; and   buffering the isotopic tracer composition to about a physiological pH.   
     
     
       13. The method of claim 12 wherein the protein is selected from the group consisting of fibrinogen, antibodies, and enzymes. 
     
     
       14. The method of claim 12 wherein the radioisotope is an isotope of an element selected from the group consisting of Rhenium, Ruthenium and Technetium. 
     
     
       15. The method of claim 14 wherein isotope is selected from the group consisting of Re-188, Re-186, Ru-97, and Tc-99m. 
     
     
       16. A method for preparing an isotopic tracer composition comprising a chelated protein or chelated fragment thereof and a radioisotope characterized by the ability to bind a protein or fragment thereof when treated with a sufficient amount of stannous phosphate, consisting of the steps of: contacting an effective amount of the radioisotope with an amount of stannous phosphate at a pH greater than 7 which is sufficient to reduce a substantial amount of the radioisotope to a lower oxidation state; and   exposing an effective amount of the chelated protein or chelated fragment thereof to the reduced radioisotope at a pH greater than 7 thereby binding the chelated protein or chelated fragment thereof to the radioisotope forming an isotopic tracer composition.   
     
     
       17. The method of claim 16 wherein the radioisotope is an isotope of an element selected from the group consisting of Rhenium, Ruthenium and Technetium. 
     
     
       18. The method of claim 17 wherein the isotope is selected from the group consisting of Re-188, Re-186, Ru-97, and Tc-99m. 
     
     
       19. A method for preparing an isotopic tracer composition comprising a chelated protein or chelated fragment thereof and a radioisotope characterized by the ability to bind a protein or fragment thereof when treated with a sufficient amount of stannous phosphate, consisting of the steps of: contacting an effective amount of the radioisotope with an amount of stannous phosphate at a pH greater than 7 which is sufficient to reduce a substantial amount of the radioisotope to a lower oxidation state;   exposing an effective amount of the chelated protein or chelated fragment thereof to the reduced radioisotope at a pH greater than 7 thereby binding the chelated protein or chelated fragment thereof to the radioisotope; and   buffering the isotopic tracer composition to about a physiological pH.   
     
     
       20. The method of claim 19 wherein the radioisotope is an isotope of an element selected from the group consisting of Rhenium, Ruthenium and Technetium. 
     
     
       21. The method of claim 20 wherein isotope is selected from the group consisting of Re-188, Re-186, Ru-97, and Tc - 99m.